linux-block.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Kristian Klausen <kristian@klausen.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: linux-block@vger.kernel.org, stable@vger.kernel.org,
	Jens Axboe <axboe@kernel.dk>, Martijn Coenen <maco@android.com>,
	open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] loop: Fix missing discard support when using LOOP_CONFIGURE
Date: Fri, 18 Jun 2021 01:26:19 +0200	[thread overview]
Message-ID: <8445d1b6-0118-37d4-c927-3b7e6ff480ea@klausen.dk> (raw)
In-Reply-To: <YMvUw3E51fvezQN/@T590>

On 18.06.2021 01.03, Ming Lei wrote:
> On Fri, Jun 18, 2021 at 12:11:57AM +0200, Kristian Klausen wrote:
>
> Commit log?

I will try to come up with a commit message. AFAIU the missing call to 
loop_config_discard() causes the block device to report "no discard 
support" (best-case) or stale/incorrect discard support (ex: if the loop 
device was configured with LOOP_SET_STATUS(64) and later LOOP_CONFIGURE).

>
>> Cc: <stable@vger.kernel.org> # 5.8.x-
>> Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl")
>> Signed-off-by: Kristian Klausen <kristian@klausen.dk>
>> ---
>> Tested like so (without the patch):
>> losetup 2.37<= uses LOOP_CONFIGURE instead of LOOP_SET_STATUS64[1]
>>
>> # fallocate -l100M disk.img
>> # rmmod loop
>> # losetup --version
>> losetup from util-linux 2.36.2
>> # losetup --find --show disk.img
>> /dev/loop0
>> # grep '' /sys/devices/virtual/block/loop0/queue/*discard*
>> /sys/devices/virtual/block/loop0/queue/discard_granularity:4096
>> /sys/devices/virtual/block/loop0/queue/discard_max_bytes:4294966784
>> /sys/devices/virtual/block/loop0/queue/discard_max_hw_bytes:4294966784
>> /sys/devices/virtual/block/loop0/queue/discard_zeroes_data:0
>> /sys/devices/virtual/block/loop0/queue/max_discard_segments:1
>> # losetup -d /dev/loop0
>> # [update util-linux]
>> # losetup --version
>> losetup from util-linux 2.37
>> # rmmod loop
>> # losetup --find --show disk.img
>> /dev/loop0
>> # grep '' /sys/devices/virtual/block/loop0/queue/*discard*
>> /sys/devices/virtual/block/loop0/queue/discard_granularity:0
>> /sys/devices/virtual/block/loop0/queue/discard_max_bytes:0
>> /sys/devices/virtual/block/loop0/queue/discard_max_hw_bytes:0
>> /sys/devices/virtual/block/loop0/queue/discard_zeroes_data:0
>> /sys/devices/virtual/block/loop0/queue/max_discard_segments:1
>>
>>
>> With the patch applied:
>>
>> # losetup --version
>> losetup from util-linux 2.37
>> # rmmod loop
>> # losetup --find --show disk.img
>> /dev/loop0
>> # grep '' /sys/devices/virtual/block/loop0/queue/*discard*
>> /sys/devices/virtual/block/loop0/queue/discard_granularity:4096
>> /sys/devices/virtual/block/loop0/queue/discard_max_bytes:4294966784
>> /sys/devices/virtual/block/loop0/queue/discard_max_hw_bytes:4294966784
>> /sys/devices/virtual/block/loop0/queue/discard_zeroes_data:0
>> /sys/devices/virtual/block/loop0/queue/max_discard_segments:1
>>
>> [1] https://github.com/karelzak/util-linux/pull/1152
>>
>>   drivers/block/loop.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
>> index 76e12f3482a9..ec957f6d8a49 100644
>> --- a/drivers/block/loop.c
>> +++ b/drivers/block/loop.c
>> @@ -1168,6 +1168,8 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
>>   	if (partscan)
>>   		lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
>>   
>> +	loop_config_discard(lo);
>> +
> It could be better to move loop_config_discard() around
> loop_update_rotational/loop_update_dio(), then we setup everything
> before updating loop as Lo_bound.

I will move it before loop_update_rotational().

>
> Otherwise, this patch looks fine.
>
>
> Thanks,
> Ming
>


      reply	other threads:[~2021-06-17 23:26 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-17 22:11 Kristian Klausen
2021-06-17 23:03 ` Ming Lei
2021-06-17 23:26   ` Kristian Klausen [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8445d1b6-0118-37d4-c927-3b7e6ff480ea@klausen.dk \
    --to=kristian@klausen.dk \
    --cc=axboe@kernel.dk \
    --cc=linux-block@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=maco@android.com \
    --cc=ming.lei@redhat.com \
    --cc=stable@vger.kernel.org \
    --subject='Re: [PATCH] loop: Fix missing discard support when using LOOP_CONFIGURE' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).